Will this work as a bedframe?

My gut feeling is no. Now, i'll look at the math...

You're basically making a floating bed supported just at one end by two joints.

Let's say your bed weighs 50 pounds (for a Twin size), you weigh 190 pounds. Add in another 40 pounds for the wood structure of the frame, the part that is holding the mattress directly.

All together, around 280 pounds. At times when you sit down, or even flop down heavily, on the bed, that force will be much greater (force equals mass times acceleration), but we'll ignore that and pretend you always sit down gently for the life of the bed.

Just looking at the 280 pounds we can consider that a distributed load, so the force can be thought of as being applied to the center of the bed. That would be around 37 inches away from those joints in the horizontal direction. And then also some number of inches not specified in the vertical direction away from the joint on the ground. I'm going to just assume, since you don't have a box spring, that will be 16 inches up. It can vary, but you'll see it doesn't really matter.

The simple math (moments of force about a point), see here, shows you're going to be applying over 600 foot pounds of force per joint on the lower ones on the floor. It is true you'd have to do specific testing on a model to find out how much force those joints can really handle. But knowing some tests already done on mortise and tenon joints, i'd have to say they won't hold that. I've seen tests done on wood done on 90 degree angle joints (stronger than what you're doing) with really thick wood dowels that failed at 500 pounds. Many fail at less.

And real world situation, you're going to be putting more force than that. You'll be sitting down heavy after a long day, there will be fatigue after years of use, you may not use the same glue with the same bonding strength... Long list of variables, with the big one being if you ever sat on the end of the bed the numbers go way higher. You're looking at around 900 foot pounds of force on each joint easily in that case. So overall, my gut says you would need more support. If you build it with just those joints holding it all in place, you'll be sleeping on the floor the first time you lay down on it.

Most 'floating beds' actually have support that goes to the half way point or further, it's just hidden from view if looked at from the side. That extra support is crucial.

/r/woodworking Thread Parent